This invention relates to an apparatus and method for electrophysiological cardiac mapping. More particularly, the invention is directed to a system based on a nonexpandable, noncontact, miniature, multielectrode catheter which is used to measure electrical potentials within a heart cavity. These measured potentials are then used, along with data on the geometric relationship between the catheter and the endocardial surface, to reconstruct maps representing endocardial electrical activity. In this regard, electrograms and isochrones are reconstructed.
While the invention is particularly directed to the art of electrophysiological cardiac mapping, and will be thus described with specific reference thereto, it will be appreciated that the invention may have usefulness in other fields and applications.
By way of background, endocardial potential mapping is a tool for studying cardiac excitation and repolarization processes. Mapping endocardial potential distribution and its evolution in time is useful for analyzing activation and repolarization patterns and for locating arrhythmogenic sites and regions of abnormal electrical activity in the heart. Accurate localization of arrhythmogenic sites is important to the success of non-pharmacological interventions, such as catheter ablation.
Unfortunately, current techniques of mapping potentials directly from the endocardium present certain difficulties. For example, the well-known “roving” probe approach is 1) limited in the number of recording sites, 2) too time consuming and 3) only operative to collect data over a plurality of heart beats, instead of a single beat. Therefore, this approach is not useful on a beat-by-beat basis to study dynamic changes in the activation process.
In addition, multiple electrode balloons or sponges have also been used to map electrical activity of the heart by way of measuring potentials within a heart cavity. Although capable of mapping the entire endocardium, these devices occlude the heart cavity and require open heart surgery, heart-lung bypass and other complicated and high risk procedures.
Another device having a multiple-spoke, basket-shaped recording catheter allows simultaneous acquisition of potential data from multiple electrodes without occluding the cavity. However, the basket is nonetheless limited in the number of electrodes so that spatial resolution is relatively low. Moreover, it is difficult to insure that all electrodes make contact with the endocardium. Also, the basket can be entangled in intracavitary structures such as the chordae tendineae. The fact that the basket must be collapsed prior to catheter withdrawal from the ventricle adds complexity and risk to this procedure.
Still another known device for detecting endocardial potentials uses an electrode array catheter that can be expanded within the heart chamber but does not occlude the heart chamber. However, this system still involves undesirable expansion of a device in the heart chamber. The expanded element may interfere with intracavity structures and adds complexity to the system because it must be collapsed before removal. Moreover, it is difficult to determine the location of the electrodes within the chamber. Also, the array may not expand as desired, leading to inaccuracies in mapping.
Taccardi et al. developed an alternative indirect mapping approach that makes use of a large (too large for clinical applications) intracavitary multielectrode catheter-probe (olive shaped or cylindrical), that can be introduced into the blood filled cavity without occluding it. The probe permits simultaneous recording of intracavitary potentials from multiple directions but, unlike the balloon, is not in direct contact with the endocardium and does not record actual endocardial potentials. The intracavitary probe potentials exhibit smoothed-out distributions and do not reflect details of the excitation (or repolarization) process that can be detected and located by direct endocardial recordings. It is highly desirable, therefore, to develop an approach for reconstructing endocardial potentials, electrograms and isochrones from data recorded with a small, non-expanding intracavitary catheter-probe that can be introduced percutaneously, does not occlude the ventricle, and/or does not require opening large structures (e.g. basket or balloon) inside the cavity.
Accordingly, it would be desirable to have available a multielectrode catheter probe that can be introduced percutaneously, without expanding inside the ventricular cavity, and provide accurate reconstructed endocardial potentials, electrograms and isochrones.
The present invention contemplates a new and improved system and method for electrophysiological cardiac mapping using a non-contact, non-expandable catheter which resolves the above referenced difficulties and others and attains the above referenced desired advantages and others.